Noninvasive CO2 Monitoring Technology & Clinical Applications Lonnie Martinez Director of Respiratory Care Swedish Medical Center Lonnie Martinez Director of Respiratory Care Swedish Medical Center

Objectives Definitions and Parameters Descriptors and Overview Interpretation – Especially Waveform Bedside Application Conscious Sedation

Capnography Respiration - The Big Picture 1 Cellular Metabolism of food into energy - O 2 consumption & CO 2 Production Transport of O 2 & CO 2 between cells and pulmonary capillaries, & diffusion from/into alveoli. Ventilation between alveoli & atmosphere 2 3

Monitoring CO 2 Elimination => Patient response to changes in Circulation Diffusion Ventilation Metabolism (CO 2 Production) Ventilation CO 2 Elimination (VCO 2 ) Transport PaCO 2 MTV

Capnography Depicts Respiration Capnography MetabolismTransportVentilation CO 2

Capnography Technical Aspects of Capnography

Capnography Capnography vs. Capnometry Capnography Measurement & display of ETCO 2 and the (CO 2 waveform) Measured by a capnograph Capnometry Measurement & display of the ETCO 2 value (no waveform) Measured by a capnometer

Capnography Mainstream Technology Sensor placed in ventilator circuit Measurement made at the patient’s airway Fast response time No water traps or tubing needed - hassle free Non-intubated patient may use Capno Masks Sensor

Capnography Sidestream Technology Sensor located away from the airway Gas moved to sensor by pump inside the monitor Use with cannula or adapt for ventilator airway Water traps, filters, or dehumidification tubing may be required

Capnography Quantitative vs. Qualitative ETCO 2 Quantitative ETCO 2 Provides actual numeric value Found in capnographs and capnometers Qualitative ETCO 2 Only provides range of values Colorimetric CO 2 detectors

Normal Capnogram - Phase I CO 2 mmHg Beginning of expiration = anatomical deadspace with no measurable CO 2 A B

Anatomical Dead Space  Anatomical Dead Space  Internal volume of the upper airways Nose Pharynx Trachea Bronchi Anatomical Deadspace Conducting Airway - No Gas Exchange

Normal Capnogram - Phase II CO 2 mmHg Mixed CO 2, rapid rise in CO 2 concentration B C

Phase II - Transitional Gas CO 2 mmHg Exhaled Volume

Normal Capnogram - Phase III CO 2 mmHg Time Alveolar Plateau, all exhaled gas took part in gas exchange End Tidal CO 2 value C D

Normal Capnogram - Phase IV CO 2 mmHg Inspiration starts, CO2 drops off rapidly E D

Capnography Increased muscular activity (shivering) Malignant hyperthermia Increased cardiac output Bicarbonate infusion Tourniquet release Effective drug therapy for bronchospasm Decreased minute ventilation Decreased muscular activity (muscle relaxants) Hypothermia Decreased cardiac output (cardiac arrest) Pulmonary embolism Bronchospasm Increased minute ventilation Physiologic Factors Affecting ETCO 2 Levels Increase in ETCO2Decrease in ETCO2

Capnography Arterial CO 2 (PaCO 2 ) From Arterial Blood Gas Sample (ABG) ETCO 2 from Capnograph Normal Arterial & ETCO 2 Values Normal PaCO 2 Values: (at sea level) mmHg Normal ETCO 2 Values: mmHg kPa %

Understanding why ETCO 2 doesn’t match the ABG is important, if you don’t understand why it doesn’t match, it erodes confidence in all of the values!!! You may throw the baby out with the bath water!!

Capnography Arterial - End Tidal CO 2 Gradient In healthy lungs the normal a- ET CO 2 gradient is 2-5 mmHg In diseased lungs, the gradient will increase due to ventilation/perfusion mismatch. Decreased cardiac function will also reduce the ETCO 2 value, due to decreased pulmonary blood flow

Capnography Deadspace Ventilated areas which do not participate in gas exchange Anatomic Deadspace (airways leading to the alveoli Total Deadspace Alveolar Deadspace (ventilated areas in the lungs) Mechanical Deadspace (artificial airways including ventilator circuits) ++

Normal V/Q CO 2 O2O2 ETCO 2 / PaCO 2 Gradient = 2 to 5 mmHg..

Shunt Perfusion – Low V/Q No exchange of O 2 or CO 2 ETCO 2 / PaCO 2 Gradient = 4 to 10 mmHg..

Dead Space Ventilation High V/Q Perfusion is the problem No exchange of O 2 or CO 2 occurs ETCO 2 / PaCO 2 Gradient is large May exceed 60 torr Ventilation is not the problem!..

Capnography Ventilation-Perfusion Relationships Relationship between air flow in the alveoli and blood flow in the pulmonary capillaries Shunt perfusion Alveoli perfused but not ventilated. Atelectasis from any reason Deadspace Ventilation Alveoli ventilated but not perfused. Cardiac Arrest or hypotension

Dead Space Ventilation PaCO 2 = 53 mmHg ETCO 2 = 33 mmHg 53 Alveoli that do not take part in gas exchange will still have no CO 2 – Therefore they will dilute the CO 2 from the alveoli that were perfused The result is a widened ETCO 2 to PaCO 2 Gradient

Capnography Clinical Application of Capnography

Capnography Value of the CO 2 Waveform Provides validation of ETCO 2 value Visual assessment of patient airway integrity Verification of proper ET tube placement ASA, JCAHO guidelines Recent CMS recommendation Assessment of ventilator, breathing circuit integrity

Capnogram – Valuable Tool CO 2 (mmHg) Alveolar Plateau established No Alveolar Plateau

Abnormal CO 2 Waveforms

Capnography Endotracheal Tube in Esophagus Possible Causes:  Missed Intubation  A normal capnogram is the best evidence that the ET tube is correctly positioned.  When the ET tube is in the esophagus, little or no CO 2 is present

Capnography Inadequate Seal Around ET Tube Possible Causes:  Leaky of deflated endotracheal or tracheostomy cuff  Artificial airway that is too small for patient  Tube could be at the vocal cords

Capnography Obstruction in Airway or Breathing Circuit Possible Causes:  Partially kinked or occluded artificial airway  Presence of foreign body in the airway  Obstruction in expiratory limb of breathing circuit  Bronchospasm

CO 2 Exhaled Volume Day 1 Day 5 Patient with Asthma

Capnography Hypoventilation - Increase in ETCO 2 Possible Causes:  Decrease in respiratory rate  Decrease in tidal volume  Increase in metabolic rate  Rapid rise in body temperature (hyperthermia)

Capnography Hyperventilation - Decrease in ETCO 2 Possible Causes:  Increase in respiratory rate  Increase in tidal volume  Decrease in metabolic rate  Fall in body temperature

Based on simple O 2 delivery style mask Allows measurement of EtCO 2 and delivery of O 2 on non- intubated patients Effective Capnogram to verify data Excellent Choice for Conscious Sedation CAPNO 2 Mask O 2 Delivery/CO 2 Mainstream Mask

Cannula O2 Delivery/ CO 2 Sidestream

Procedural Sedation Capnography is the logical device to monitor ventilation during procedural sedation Why? Airway problems are primary causes of morbidity associated with sedation/analgesia Drug induced respiratory depression Airway obstruction

Procedural Sedation with O2 Capnography is a valuable monitoring tool to to detect respiratory events that could culminate in hypoxia Why? Patients in the ED are often on supplemental oxygen Increased FIO 2 may mask the decrease in ventilation early on if you are only observing pulse oximetry

Procedural Sedation Capnography offers a safety net A decrease in ventilation during procedural sedation almost always precedes a drop in saturation The decrease in ETCO 2, or a change in the shape of the capnogram will indicate a change in ventilation or airway integrity This safety net can facilitate early intervention and avoid subsequent hypoxemia

CPR

A cool story…Ventilator Dyssynchrony

Conclusion Improved Patient Monitoring It’s not just about the Number Waveform Interpretation Helps with Differential DX Clinical Application